Photon echo quantum memory with complete use of natural inhomogeneous broadening

The photon echo quantum memory is based on a controlled rephasing of the atomic coherence excited by signal light field in the inhomogeneously broadened resonant line. Here, we propose a novel active mechanism of the atomic rephasing which provides a perfect retrieval of the stored light field in the photon echo quantum memory for arbitrary initial inhomogeneous broadening of the resonant line. It is shown that the rephasing mechanism can exploit all resonant atoms which maximally increases an optical depth of the resonant transition that is one of the critical parameters for realization of highly efficient quantum memory. We also demonstrate that the rephasing mechanism can be used for various realizations of the photon echo quantum memory that opens a wide road for its practical realization.Comment: 6 pages, 4 figure

Kinematically detected polar rings/disks in blue compact dwarf galaxies

Polar ring galaxies are systems with nearly orthogonally rotated components. We have found the gas on polar (or strongly inclined) orbits in two BCD galaxies using ionized gas velocity fields taken with a Fabry-Perot interferometer of the SAO RAS 6-m telescope. Our analysis shows that all ionized gas in Mrk 33 is concentrated in a compact disk (3 kpc in diameter) which rotates in the polar plane relative to the main stellar body. The gaseous disk in Mrk 370 has a more complex structure with a heavily warped innermost part. The presence of polar gaseous structures supports an idea that current the burst of star formation in these galaxies is due to the external gas accretion or merging. A possible fraction of polar structures among BCD galaxies seems to be very large (up to 10-15%)Comment: to appear in the proceedings of the conference "A Universe of dwarf galaxies" (Lyon, June 14-18, 2010

A synchrotron superbubble in the IC 10 Galaxy: a hypernova remnant?

The nature of the synchrotron superbubble in the IC 10 galaxy is discussed using the results of our investigation of its ionized gas structure, kinematics, and emission spectrum from observations made with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, and based on our analysis of the radio emission of the region. The hypernova explosion is shown to be a more plausible mechanism of the formation of the synchrotron superbubble compared with the earlier proposed model of multiple supernova explosions. A compact remnant of this hypernova may be identified with the well known X-ray binary X-1 -- an accreting black hole.Comment: 4 pages, 3 EPS figures, Accepted to MNRAS (in Letters